CROSS REFERENCE TO RELATED APPLICATIONS
FIELD
[0002] The present disclosure relates generally to water pumps for motor vehicles. More
specifically, the present disclosure relates to a variable flow electric water pump
equipped with an axially-moveable rotor/impeller assembly.
BACKGROUND
[0003] This section provides background information related to the present disclosure which
is not necessarily prior art.
[0004] As is well known, water pumps are typically used in motor vehicles as part of a thermal
management system for pumping a liquid coolant to facilitate heat transfer between
the coolant and the internal combustion engine during vehicle warm-up and operation.
Most commonly, a centrifugal water pump having a rotary pump member, such as an impeller,
is configured to draw the coolant into an axial inlet and discharge the coolant through
a radial discharge outlet. In many vehicular arrangements, the impeller is fixed to
an impeller shaft that is rotatably driven (via an accessory drive system) by the
crankshaft of the engine. Thus, the impeller speed is directly proportional to the
engine speed. To provide a variable flow feature to such shaft-driven water pumps,
it is known to permit limited axial displacement of the impeller within the pump chamber.
For example,
U.S. Patent No. 7,789,049 discloses a water pump having an axially-moveable impeller that is spline mounted
to the engine-driven shaft, and an electromagnetic actuator operable to control axial
movement of the impeller between extended and retracted positions along the shaft
so as to variably regulate the fluid flow characteristic between the fluid inlet and
the discharge outlet. Similarly,
U.S. Patent No. 5,800,120 discloses a water pump having a shaft-driven impeller equipped with axially-moveable
blades, the position of which is controlled via a hydraulic actuator.
[0005] It is also well known to install an auxiliary water pump, such as an electric water
pump, in the engine coolant system to provide augmented control over the fluid flow.
Generally, electric water pumps include an electric motor having a stationary stator
and a rotor that is drivingly coupled to the impeller. Examples of electric water
pumps are disclosed in commonly-owned U.S. Publication No.
US2013/0259720 titled "Electric Water Pump With Stator Cooling" and U.S. Publication No.
US2014/0017073 titled "Submerged Rotor Electric Water Pump with Structural Wetsleeve".
[0006] One drawback associated with many conventional electric water pumps is the need to
provide a rotor encoder or another type of speed sensor within the electric motor
to assist in accurate low speed (i.e. less than 600 RPM) pump control via a closed
loop motor control system. Additionally, a need exists to provide variable flow at
such low speeds that is not directly proportional to motor speed in an effort to meet
customer expectations.
[0007] DE2510787 A1 discloses a variable flow electric water pump for a heating system in a house. The
electric water pump comprises a pump housing defining a fluid chamber and a motor
chamber, an electric motor with a stationary stator assembly and a rotor unit with
a rotor shaft and a pump member fixed to the rotor shaft and a biasing arrangement
for normally locating the rotor in a first position that is axially offset relative
to said stator assembly for locating said pump member in a retracted position at a
low rotor speed.
[0008] EP3076020A1 discloses a water pump with an electrical machine in a housing. The impeller is movable
mounted to provide two functional positions for a full flow or a zero flow through
inlet and outlet. The impeller is moved by hydraulic force over the impellor rotating
with a high speed, the counterforce is either a magnetic force or a spring load.
[0009] In view of the above, a need exists in the art to design and develop simplified and
low-cost electric water pumps capable of providing variable flow characteristics and
which can be easily substituted for otherwise conventional electric water pumps in
motor vehicle applications.
SUMMARY
[0010] This section provides a general summary of the disclosure and is not intended to
act as a comprehensive and exhaustive disclosure of its full scope or all of its features,
advantages, objectives and aspects. The scope of the invention is solely defined by
the appended claims.
[0011] It is an objective of the present disclosure to provide an electric water pump that
meets the above-identified needs and provides a technological advancement over conventional
electric water pumps.
[0012] It is another objective of the present disclosure to provide an electric water pump
equipped with an electric motor having a stationary stator assembly and an axially-moveable
rotor unit adapted to cause concurrent axial movement of a rotary pump member within
a pump chamber for variably regulating fluid flow between an inlet and an outlet communicating
with the pump chamber.
[0013] It is similar objective of the present disclosure to provide an electric water pump
having a rotor/impeller assembly that is axially moveable relative to a stationary
stator assembly for varying the size of a clearance gap between a volute in the pump
chamber and the impeller. It is a related objective of the present disclosure to control
movement of the rotor/impeller assembly so as to provide a low flow output at low
rotor speeds and a high flow output at high rotor speeds. In this regard, the rotor/impeller
assembly is located in a low flow position relative to the stator assembly when rotated
at low rotor speeds and in a high flow position relative to the stator assembly when
rotated at high rotor speeds.
[0014] In accordance with a first embodiment of the invention of an electric water pump
constructed and functional in accordance with the objectives of the present disclosure,
the rotor/impeller assembly is normally biased toward its low flow position by a mechanical
biasing arrangement disposed between the rotor unit and a stationary member within
a pump housing. Movement of the rotor/impeller assembly from its low flow position
toward its high flow position is a result of a pressure differential (ΔP) generated
between upper (i.e. outer) and lower (i.e. inner) portions of the impeller and which
is a function of the rotary speed of the rotor/impeller assembly.
[0015] In accordance with a second embodiment not part of the invention of an electric water
pump constructed and functional in accordance with the objectives of the present disclosure,
the rotor/impeller assembly is normally located in its low flow position by a magnetic
biasing arrangement provided by an axially-offset magnetic field between the stator
assembly and the rotor unit that is established by rotor magnets having an increased
length in the direction of the impeller so as to provide a centering relationship
with the stator assembly during low speed operation.
[0016] The present disclosure is directed to a variable flow electric water 1 according
to claim 1.
[0017] The variable flow electric water pump of the present disclosure is equipped with
a mechanical biasing arrangement configured to normally exert a biasing force on the
rotor unit selected to bias the rotor unit toward its first position. The mechanical
biasing arrangement includes a mechanical biasing member, such as one or more spring
members, disposed between an upper portion of the rotor unit and a stationary member
or portion of the pump housing.
[0018] The variable flow electric water pump of the present disclosure can optionally be
equipped with a magnetic biasing arrangement configured to normally locate the rotor
unit in its first position. This configuration is not part of the invention.
[0019] The variable flow electric water pump of the present disclosure includes an interface
formed in the pump housing between the fluid inlet and the discharge outlet defining
a flange surface. The impeller is configured to include an outer rim surfaced aligned
with the flange surface such that a first larger clearance gap is established therebetween
when the impeller is located in its retracted position. The first larger clearance
gap functions to establish a low flow characteristic when the impeller is driven at
the low impeller speeds by the electric motor. In contrast, a second smaller clearance
gap is established when the impeller is located in its extended position so as to
create a high flow characteristic when the impeller is driven by the electric motor
at the high impeller speeds.
[0020] Further areas of applicability will become apparent from the detailed description
provided herein. As noted, the description of the objectives, aspects, features and
specific embodiments disclosed in this summary are intended for purposes of illustration
only and are not intended to limit the scope of the present disclosure. The scope
of the invention is solely defined by the appended claims.
DRAWINGS
[0021] The drawings described herein are for illustrative purposes only of selected embodiments
and not all possible implementations and, as such, are not intended to limit the scope
of the present disclosure.
FIG. 1 is a sectional view of a variable flow electric water pump constructed in accordance
with a first embodiment of the present invention to include a mechanically-biased
rotor/impeller assembly which is shown located in a first or low flow position relative
to a stationary stator assembly;
FIG. 2 is another sectional view of the variable flow electric water pump shown in
FIG. 1 now illustrating the spring-biased rotor/impeller assembly located in a second
or high flow position relative to the stator assembly;
FIG. 3 is a graph illustrating the low-speed flow characteristics provided by the
variable flow electric water pump shown in FIGS. 1 and 2 in comparison to a conventional
fixed flow electric water pump;
FIG. 4 is a sectional view of a variable flow electric water pump constructed in accordance
with a second embodiment of the present disclosure not part of the invention to include
a magnetically-biased rotor/impeller assembly which is shown located in a first or
low flow position relative to the stationary stator assembly;
FIG. 5 is another sectional view of the variable flow electric water pump shown in
FIG. 4 now illustrating the rotor/impeller assembly located in a second or high flow
position relative to the stator assembly; and
FIGS. 6A and 6B are a partial sectional view of a slightly modified version of the
variable flow electric water pump of FIGS. 1 and 2.
[0022] Corresponding reference numerals indicate corresponding components throughout the
several views of the drawings.
DETAILED DESCRIPTION
[0023] Example embodiments will now be more fully describe with reference to the accompanying
drawings. However, the following description is merely exemplary in nature and is
not intended to limit the present disclosure, its subject matter, applications or
uses. To this end, example embodiments of an electric water pump are provided so that
this disclosure will be thorough and will fully convey the scope to those skilled
in this art. Numerous specific details are set forth, such as examples of specific
components, devices and methods to provide a thorough understanding of the embodiments
in many different forms, and such should not be construed to limit the intended scope
of protection afforded by this disclosure. As is understood, some well-known processes,
structures and technologies are not described in detail herein in view of the understanding
afforded thereto by those skilled in this art.
[0024] In general, the present disclosure relates to an electric pump and, more particularly,
to an electric water pump of the type applicable and well-suited for use and installation
in motor vehicles for pumping a liquid coolant through an engine cooling system. However,
the teachings provided herein are considered to be adaptable to any other electric
pump required to move a medium (i.e. air, water, coolant, oil, etc.) within a pumping
system requiring a variable flow capability.
[0025] With particular reference to FIGS. 1 and 2 of the drawings, an electric water pump
10 constructed and functional in accordance with a first embodiment of the present
invention will now be described in greater detail. Pump 10 generally includes a pump
housing 12, an electric motor 14, and a pump unit 16. Pump housing 12 is shown in
this non-limiting example to include a cylindrical outer housing 18, a first or bottom
cap 20, and a second or top cap 22. Outer housing 18 is generally cup-shaped and includes
an open end section 24 to which bottom cap 20 is secured, and an end plate section
26 to which top cap 22 is secured. End plate section 26 of outer housing 18 is formed
to define a raised annular rim 28 extending from a planar mounting surface 30. A central
pump pocket 32 is formed in rim 28 and is aligned on the longitudinal axis "A" of
pump 10. A pair of internal annular bosses 34 and 36 also extend from end plate section
26 of outer housing 18 and are aligned with the longitudinal axis. A thorough bore
38 extends between pump pocket 32 and a bearing pocket 40 associated with annular
boss 34.
[0026] Bottom cap 20 is configured, in this non-limiting embodiment, to include an annular
rim 44 extending from a planar mounting surface 46, and an elongated cylindrical hub
48, both of which are concentric with the longitudinal axis. End section 24 of outer
housing 18 includes an inner diameter wall surface 50 configured to be pressed against
an outer diameter surface 52 of annular rim 44. End section 24 also includes a planar
end surface 54 configured to engage mounting surface 46 on bottom cap 20. While not
specifically shown, a suitable fastening arrangement is provided to secure bottom
cap 20 to outer housing 18 so as to define an internal motor chamber 56. A blind bore
58 is formed in hub 48 and further defines a bearing pocket 60.
[0027] Top cap 22 is shown, in this non-limiting embodiment, configured to include an axially-extending
tubular section 64 defining a fluid inlet 66, a radially-extending tubular section
68 defining a fluid discharge outlet 70, and a volute section 72 defining an impeller
cavity 74 in fluid communication with fluid inlet 66 and discharge outlet 70. An interface
76 is formed in top cap 22 between fluid inlet 66 and impeller cavity 74 and includes
a first flange surface 78 and a second flange surface 80. Top cap 22 includes a stepped
flange section 82 configured to enclose a portion of raised rim 28 on end plate section
26 of outer housing 18. Top cap 22 also includes a planar inner mounting surface 84
configured to engage outer mounting surface 30 on outer housing 18. Suitable fasteners,
such as a plurality of bolts 86, are provided for securely connecting top cap 22 to
outer housing 18.
[0028] With continued reference to FIGS. 1 and 2, electric motor 14 is generally shown,
in this non-limiting embodiment, to include a stator assembly 90, a rotor unit 92,
and a sleeve 94. Sleeve 94 has a first end section 96 engaging end plate section 26
of outer housing 18, a second end section 98 surrounding a portion of hub 48 on bottom
cap 20, and an elongated intermediate sleeve section 100 therebetween. An O-ring seal
102 is provided between annular rim 36 of end plate section 26 and first end section
96 of sleeve 94. Sleeve 94 is configured to delineate motor chamber 56 into a toroidal
stator cavity 56A and a cylindrical rotor cavity 56B. Stator assembly 90 is located
within stator cavity 56A and is configured to be non-moveable (i.e. stationary) therein.
Rotor unit 92 is located within rotor cavity 56B and is configured to be both rotatable
and axially moveable therein, as will be detailed hereinafter with greater specificity.
[0029] Stator assembly 90 includes, in this non-limiting embodiment, a coil winding 106
and a plurality or stack of plates 108 retained on a stator cage 110. Stator cage
110 in non-moveably mounted to outer housing 18 and/or sleeve 94 within stator cavity
56A.
[0030] Rotor unit 92 is shown, in this non-limiting embodiment, to include a rotor shaft
114 and a plurality of circumferentially-aligned permanent magnets 116 retained by
or encapsulated in a rotor shell 118. An annular magnetic air gap 120 is established
between intermediate sleeve segment 100 of sleeve 94 and rotor unit 92. The components
of rotor unit 92 are fixed to rotor shaft 114 for common rotation about the longitudinal
axis. A first or lower end portion 114A of rotor shaft 114 is disposed in blind bore
58 formed in bottom cap 20 and is supported for rotary and axial movement therein
by a first or lower guide bushing 122 retained in bearing pocket 60. Likewise, a second
or upper end portion 114B of rotor shaft 114 extends through throughbore 38 and into
impeller cavity 74. End portion 114B of rotor shaft 114 is supported for rotary and
axial movement by a second or upper guide bushing 124 retained in bearing pocket 40
formed in annular boss 34.
[0031] Pump unit 16 is shown, in this non-limiting embodiment, to include a rotary pump
member, such as an impeller 126, that is rigidly fixed to second end portion 114B
of rotor shaft 114 for rotation within pump pocket 32. Impeller 126 is configured
to include a central hub segment 128, a first or lower rim segment 130 extending radially
from hub segment 128, a second or upper rim segment 132, and a plurality of contoured
impeller blades 134 extending between lower rim segment 130 and upper rim segment
132. The actual number of impeller blades 134 and their particular contoured configuration
(i.e. profile, shape, thickness, etc.) can be selected to provide the desired flow
characteristic for a specific pump application. Upper rim segment 132 is configured
to define a first rim surface 136 that is generally aligned with first flange surface
78 of volute interface 76, and define a second rim surface 138 that is generally aligned
with second flange surface 80.
[0032] In accordance with the present disclosure, a rotor/impeller assembly 150 (comprised
of rotor unit 92, rotor shaft 114 and impeller 126) is moveable axially with respect
to stator assembly 90 and inlet/volute interface 76 to provide a means for varying
the flow characteristics of pump 10. In this regard, FIGS. 1 and 2 further illustrate
pump 10 to include a mechanical biasing arrangement 152 acting between rotor unit
92 and a stationary component or portion of pump housing 12. In particular, mechanical
biasing arrangement 152 is shown, in the non-limiting embodiment, to include a thrust
washer 154 fixed to annular boss 34 (or abutting guide bushing 124) and a biasing
member 156 acting between thrust washer 154 and an upper portion of rotor unit 92.
In the non-limiting embodiment shown, biasing member 156 is a helical coil spring
surrounding rotor shaft 114 and configured to apply a predefined spring load (i.e.
"preload") on rotor unit 92 for normally biasing rotor unit 92 toward a first position
within rotor cavity 56B, as shown in FIG. 1. In this first position, rotor unit 92
is axially offset relative to stator assembly 90. Since impeller 126 is fixed via
rotor shaft 114 to rotor unit 92, impeller 126 is located in a "retracted" position
when rotor unit 92 is located in its first position. As such, rotor/impeller assembly
150 is defined to be located in a "low flow" position within pump 10.
[0033] As seen in FIG. 1, with rotor/impellor assembly 150 located in its low flow position,
a small clearance "Xi", is established between a lower surface 140 of impeller hub
128 and a bottom surface 142 of impeller pocket 32. In contrast, a large clearance
"Yi" is established between corresponding interface surfaces 78, 80 and impeller rim
surfaces 136, 138. The preload provided by biasing member 156 is selected to establish
this offset relationship shown in FIG. 1 between stator assembly 90 and rotor unit
92 when the rotor shaft speeds are low so as to increase the clearance gap "Y" between
impeller 126 and volute interface 76 to intentionally provide decreased pump efficiency
and reduced flow.
[0034] In contrast to the arrangement shown in FIG. 1, FIG. 2 illustrates pump 10 when rotor
shaft 114 is driven at a higher rotary speed. Specifically, when impeller 126 is rotated
at higher speeds, a fluid pressure differential across impellor 126 acts to compress
biasing member 156 which permits axial movement of rotor/impeller assembly 150 to
a "high-flow" position (FIG. 2). With rotor/impeller assembly 150 located in its high
flow position, rotor unit 92 is located in a second position relative to stator assembly
90 and impeller 126 is located in an "extended" position relative to volute interface
76. In its second position, rotor unit 92 is axially aligned with stator assembly
90 such that a large clearance "X
2" is established between lower surface 140 of impeller hub 128 and bottom surface
142 of impeller pocket 32 while, concomitantly, a small clearance "Y
2" is established between corresponding interface surfaces 78, 80 and impeller rim
surfaces 136, 138. The counterforce generated to oppose and overcome the preload of
biasing member 156 is a result of the pressure differential (ΔP) generated when impeller
126 is rotated at higher speed.
[0035] In one non-limiting embodiment, the clearance gap "Y
1" is in the range of 3 to 5 mm at low impeller rotary speeds in the range of 400 to
600 RPM. In contrast, the clearance gap "Y
2" is in the range of 0.3 to 0.6 mm at higher impellor rotary speeds. FIG. 3 provides
a graphical illustration of the flow vs speed characteristics for a conventional electric
water pump with a fixed rotor/impeller assembly (see line 160) in comparison to pump
10 of the present disclosure (see line 162). What is evident is that the reduced efficiency
provided by spring-biasing rotary/impeller assembly 150 to its low flow position (FIG.
1) results in reduced flow rates (LPM) at lower pump speeds. The illustration further
illustrates that upon movement of rotor/impeller assembly 150 to its high flow position
(FIG. 2), the flow vs. speed characteristics of pump 10 tend to align with those of
the conventional pump, identified in this non-limiting embodiment as point "P".
[0036] Based on the above, the present disclosure provides a unique and non-obvious variant
of an electric water pump 10 that is configured to generate lower flow at low rotor
speeds as well as generate high flow at higher rotor speeds. It is contemplated that
the preload applied by biasing member 156 to rotor unit 92 can be calibrated based
on pump speed so as to maintain rotor/impeller assembly 150 in its low flow position
until increased pumping efficiency is required.
[0037] Referring now to FIGS. 4 and 5, a second embodiment not part of the invention of
an electric water pump 10' constructed and functional in accordance with the present
disclosure will be disclosed. Based on the similarity of a majority of the components
associated with water pumps 10, 10', common reference numbers are used with the exception
that primed reference numerals identified slightly modified components. In general,
pump 10' does not rely on spring-biasing arrangement 152 to provide axial movement
of rotor/impeller assembly 150', but rather utilizes a magnetic biasing arrangement
152' provided by an axially-offset magnetic field arrangement between rotor unit 92'
and stator assembly 90. In particular, rotor unit 92' is shown equipped with a plurality
of elongated magnets 116' having extended end segments 116A extending axially outwardly
from the top portion of rotor unit 92'. Under normal circumstances, the center of
magnets 116' will naturally align with stator assembly 90, as shown in FIG. 4, so
as to locate rotor/impeller assembly 150' in the low flow position establishing clearance
X
1, and Y
1, similar to those clearances associated with pump 10 of FIG. 1. As noted previously,
rotor unit 92' is located in its first position relative to stator assembly 90 and
impeller 126 is located in its retracted position relative to volute interface 76
when rotor/impeller assembly 150 is in its low flow position. This "self-centering"
action at low rotor speeds is caused by the centering behavior of the magnetic flux
associated with the generated magnetic field.
[0038] In contract to FIG. 4, FIG. 5 illustrates pump 10' when rotor unit 92' is driven
at a higher speed which causes the pressure differential (ΔP) across impeller 126
to forcibly move rotor/impeller assembly 150' in an upward direction to its second
or extended position, thereby establishing clearances X
2, Y
2 similar to pump 10 of FIG 2. Again, rotor unit 92' is located in its second position
relative to stator assembly 90 while impeller 126 is located in its extended position
relative to volute interface 76. Thus, pump 10' provides a magnetic biasing arrangement
as an option to the mechanical biasing arrangement associated with pump 10. Line "B"
in FIG. 5 identifies the stator's center magnetic field aligned with the rotor's center
magnetic field. The clearance "D" in FIG. 4 identifies an example amount of magnetic
offset between the rotor's center magnetic field and the stator's center magnetic
field.
[0039] While pump 10 was illustrated to include a helical coil spring as biasing member
156 those skilled in the art recognize that other types and/or combinations of biasing
devices configured to normally bias rotor/impeller assembly 150 to its low flow position
during low speed/low flow operation can be employed. In addition, a combination of
the spring-biased arrangement 152 of FIGS. 1 and 2 can be integrated with the magnetic
field arrangement 152' of FIGS. 4 and 5 to provide a hybrid variant of yet another
embodiment of an electric water pump that is within the anticipated scope of this
disclosure.
[0040] While not expressly shown, those skilled in the art will recognize that electric
pumps 10, 10' would be equipped with a controller device which functions to control
operation of electric motor 12 and the rotational speed of impeller 126. The controller
device may include an electronic circuit board (ECB) electrically connected to stator
assembly 90 and which can be mounted within pump housing 18.
[0041] Referring to FIGS. 6A and 6B, another alternative embodiment of the invention of
an electric water pump 10" is shown which is generally similar to electric water pump
10 of FIGS. 1 and 2 with the exception that impeller 126" now includes a molded-in
sleeve 170 within which end portion 114B of rotor shaft 114 is pressed into. In addition,
mechanical biasing arrangement 152" now includes a plurality of stacked wave or spring
washers 172, such as Belleville washers, surrounding rotor shaft 114 and being disposed
between a top portion of rotor unit 92 and thrust washer 154. Otherwise, the structure
and function of water pump 10" is generally similar to that of water pump 10. While
specific aspects, features and arrangements have been described in the specification
and illustrated in the drawings, it will be understood that various changes can be
made and equivalent elements be substituted therein without departing from the scope
of the teachings associated with the present disclosure.
1. A variable flow electric water pump (10) for use in an engine coolant system of a
motor vehicle, the electric water pump (10) comprising:
a pump housing (12) defining a fluid chamber and a motor chamber (56), said fluid
chamber including a fluid inlet (66) and a discharge outlet (70) for providing flow
of a coolant through said fluid chamber;
an electric motor (14) disposed within said motor chamber (56) of said pump housing
(12) and including a stationary stator (90) assembly and a rotor unit (92) having
a rotor shaft (114) supported for rotation about a longitudinal axis and extending
into said fluid chamber;
a pump member (16) fixed to said rotor shaft (114) for rotation in said fluid chamber
and operable to pump coolant from said fluid inlet (66) to said discharge outlet (70);
and
a biasing arrangement (152) for normally locating said rotor unit (92) in a first
position that is axially offset relative to said stator assembly (90) for locating
said pump member (16) in a retracted position within said fluid chamber to provide
a low flow characteristic between said fluid inlet (66) and said discharge outlet
(70) when said pump member (16) is rotatably driven by said rotor shaft (114) at a
low rotor speed;
wherein rotation of said pump member (16) at a high impeller speed causes said rotor
unit (92) to move into a second position axially aligned with said stator assembly
(90) and causes said pump member (16) to move into an extended position within said
fluid chamber to provide a high flow characteristic between said fluid inlet (66)
and said discharge outlet (70),
wherein said biasing arrangement (152) is a mechanical biasing arrangement including
a biasing member (156) configured to exert a preload on said rotor unit (92) and said
pump housing (12) includes an interface between said fluid inlet (66) and said fluid
chamber defining a first and a second flange surface (78,80), wherein said impeller
(126) having an upper first and second rim surface (136, 138) aligned with said first
and second flange surface (78,80) of said pump housing, wherein a large clearance
gap (Y1) is established between said upper first rim surface (136) of said impeller
(126) and said first flange surface (78) of said pump housing (12) when said impeller
(126) is located in its retracted position, and wherein said large clearance gap (Y1)
is configured to decrease the coolant flow rate between said fluid inlet (66) and
said discharge outlet (70).
2. The electric water pump of Claim 1, wherein a small clearance gap (Y2) is established
between said first flange surface (78) of said pump housing (12) and said first rim
surface (136) of said impeller (126) when said impeller (126) is located in its extended
position, and wherein said small clearance gap (Y2) is configured to increase the
coolant flow rate between said fluid inlet and said discharge outlet.
3. The electric water pump (10) of Claim 1,
wherein said biasing member (156) is a coil spring disposed between a portion of said
pump housing (12) and said rotor unit (92).
4. The electric water pump (10) of Claim 1 to 3, wherein the mechanical biasing arrangement
(152) is acting between rotor unit (92) and a stationary component or portion of pump
housing (12).
5. The electric water pump (10) of one of the Claims 1 to 4, wherein an annular boss
(34) extends from end plate section (26) of pump housing (12), and a thrust washer
(154) is fixed to annular boss (34) and the biasing member (156) acts between thrust
washer (154) and an upper portion of rotor unit (92).
6. The electric water pump (10) of Claim 1, wherein said rotor shaft (114) is axially
moveable relative to said pump housing (12) and has a first end (114A) slideably and
rotatably supported by a first guide bushing (122) and a second end (114B) slideably
and rotatably supported by a second guide bushing (124).
7. The electric water pump (10) of Claim 6, wherein i a pressure differential established
across said impeller in response to increasing impeller speed is operable to cause
said impeller (126) to move from its retracted position into its extended position,
and wherein such axial movement of said impeller causes concurrent axial movement
of said rotor unit (92) relative to said stator assembly (90) from its first position
into its second position.
8. The electric water pump of Claim 1, wherein a pressure differential established across
said pump member in response to increasing rotor unit speed is operable to cause said
pump member to move from its retracted position into its extended position, and wherein
such axial movement of said pump member causes concurrent axial movement of said rotor
unit: relative to said stator assembly from its first position into its second position.
1. Elektrische Wasserpumpe (10) mit variablem Durchfluss zur Verwendung in einem Kraftmaschinenkühlmittelsystem
eines Motorfahrzeugs, wobei die elektrische Wasserpumpe (10) umfasst:
ein Pumpengehäuse (12), definierend eine Fluidkammer und eine Motorkammer (56), wobei
die Fluidkammer einen Fluideinlass (66) und einen Ableitungsauslass (70) zum Bereitstellen
eines Stroms eines Kühlmittels durch die Fluidkammer einschließt;
einen elektrischen Motor (14), angeordnet innerhalb der Motorkammer (56) des Pumpengehäuses
(12) und einschließend eine stationäre Statoranordnung (90) und eine Rotoreinheit
(92), die eine Rotorwelle (114), gestützt für Drehung um eine Längsachse und sich
in die Fluidkammer erstreckend, aufweist;
ein Pumpenelement (16), befestigt an der Rotorwelle (114) für Drehung in der Fluidkammer
und betreibbar, um Kühlmittel von dem Fluideinlass (66) zu dem Ableitungsauslass (70)
zu pumpen; und
eine Vorspannanordnung (152), um die Rotoreinheit (92) normal in einer ersten Position
zu platzieren, die relativ zu der Statoranordnung (90) axial versetzt ist, um das
Pumpenelement (16) in einer zurückgezogenen Position innerhalb der Fluidkammer zu
positionieren, um zwischen dem Fluideinlass (66) und dem Ableitungsauslass (70) eine
niedrige Durchflusskennlinie bereitzustellen, wenn das Pumpenelement (16) von der
Rotorwelle (114) mit einer niedrigen Rotordrehzahl drehbar angetrieben wird;
wobei Drehung des Pumpenelements (16) bei einer hohen Pumpenraddrehzahl die Rotoreinheit
(92) veranlasst, sich in eine zweite Position, axial ausgerichtet auf die Statoranordnung
(90) zu bewegen, und das Pumpenelement (16) veranlasst, sich in eine ausgefahrene
Position innerhalb der Fluidkammer zu bewegen, um eine hohe Durchflusskennlinie zwischen
dem Fluideinlass (66) und dem Ableitungsauslass (70) bereitzustellen,
wobei die Vorspannanordnung (152) eine mechanische Vorspannanordnung ist, die ein
Vorspannelement (156), dazu ausgelegt, eine Vorlast auf die Rotoreinheit (92) auszuüben,
einschließt, und das Pumpengehäuse (12) eine Schnittstelle zwischen dem Fluideinlass
(66) und der Fluidkammer, definierend eine erste und zweite Flanschoberfläche (78,
80), einschließt, wobei das Pumpenrad (126) eine obere erste und zweite Randoberfläche
(136, 138), ausgerichtet auf die erste und zweite Flanschoberfläche (78, 80) des Pumpengehäuses,
aufweist, wobei zwischen der oberen ersten Randoberfläche (136) des Pumpenrades (126)
und der ersten Flanschoberfläche (78) des Pumpengehäuses (12) ein großer Abstandsspalt
(Y1) aufgebaut ist, wenn sich das Pumpenrad (126) in seiner zurückgezogenen Position
befindet, und wobei der große Abstandsspalt (Y1) dazu ausgelegt ist, die Kühlmitteldurchflussrate
zwischen dem Fluideinlass (66) und dem Ableitungsauslass (70) zu verringern.
2. Elektrische Wasserpumpe nach Anspruch 1, wobei zwischen der ersten Flanschoberfläche
(78) des Pumpengehäuses (12) und der ersten Randoberfläche (136) des Pumpenrades (126)
ein kleiner Abstandsspalt (Y2) aufgebaut ist, wenn sich das Pumpenrad (126) in seiner
ausgefahrenen Position befindet, und wobei der kleine Abstandsspalt (Y2) dazu ausgelegt
ist, die Kühlmitteldurchflussrate zwischen dem Fluideinlass (und dem Ableitungsauslass
(zu erhöhen.
3. Elektrische Wasserpumpe (10) nach Anspruch 1,
wobei das Vorspannelement (156) eine Spiralfeder, angeordnet zwischen einer Partie
des Pumpengehäuses (12) und der Rotoreinheit (92), ist.
4. Elektrische Wasserpumpe (10) nach Anspruch 1 bis 3, wobei die mechanische Vorspannanordnung
(152) zwischen der Rotoreinheit (92) und einer stationären Komponente oder Partie
des Pumpengehäuses (12) agiert.
5. Elektrische Wasserpumpe (10) nach einem der Ansprüche 1 bis 4, wobei sich eine ringförmige
Auswölbung (34) von einem Endplattenabschnitt (26) des Pumpengehäuses (12) erstreckt
und eine Druckscheibe (154) an der ringförmigen Auswölbung (34) befestigt ist und
das Vorspannelement (156) zwischen dem Druckring (154) und einer oberen Partie der
Rotoreinheit (92) agiert.
6. Elektrische Wasserpumpe (10) nach Anspruch 1, wobei die Rotorwelle (114) relativ zu
dem Pumpengehäuse (12) axial bewegbar ist und ein erstes Ende (114A), gleitbar und
drehbar gestützt von einer ersten Führungsbuchse (122), und ein zweites Ende (114B),
gleitbar und drehbar gestützt von einer zweiten Führungsbuchse (124), aufweist.
7. Elektrische Wasserpumpe (10) nach Anspruch 6, wobei ein über das Pumpenrad in Reaktion
auf eine Erhöhung der Pumpenraddrehzahl aufgebautes Druckdifferenzial operierbar ist,
um das Pumpenrad (126) zu veranlassen, sich von seiner zurückgezogenen Position in
seine ausgefahrene Position zu bewegen, wobei eine solche axiale Bewegung des Pumpenrades
eine gleichzeitige axiale Bewegung der Rotoreinheit (92) relativ zur Statoranordnung
(90) aus ihrer ersten Position in ihre zweite Position veranlasst.
8. Elektrische Wasserpumpe nach Anspruch 1, wobei ein über das Pumpenelement in Reaktion
auf eine Erhöhung der Rotoreinheitdrehzahl aufgebautes Druckdifferential operierbar
ist, um das Pumpenelement zu veranlassen, sich von seiner zurückgezogenen Position
in seine ausgefahrene Position zu bewegen, und wobei eine solche axiale Bewegung des
Pumpenelements eine gleichzeitige axiale Bewegung der Rotoreinheit relativ zur Statoranordnung
aus ihrer ersten Position in ihre zweite Position veranlasst.
1. Pompe à eau électrique à débit variable (10) à utiliser dans un système de refroidissement
pour moteur d'un véhicule à moteur, la pompe à eau électrique (10) comprenant :
un corps de pompe (12) définissant une chambre à fluide hydraulique et une chambre
de moteur (56), ladite chambre à fluide hydraulique incluant une entrée de fluide
(66) et une sortie de décharge (70) pour assurer le débit d'un liquide de refroidissement
à travers ladite chambre à fluide hydraulique ;
un moteur électrique (14) disposé dans ladite chambre de moteur (56) dudit corps de
pompe (12) et incluant un ensemble de stator stationnaire (90) et une unité de rotor
(92) ayant un arbre de rotor (114) soutenu pour la rotation autour d'un axe longitudinal
et s'étendant à l'intérieur de ladite chambre à fluide hydraulique ;
un organe de pompe (16) fixé sur ledit arbre de rotor (114) pour l'entraîner en rotation
dans ladite chambre à fluide hydraulique et actionnable pour pomper le liquide de
refroidissement de ladite entrée de fluide (66) vers ladite sortie de décharge (70)
; et
un dispositif de polarisation (152) pour positionner normalement ladite unité de rotor
(92) dans une première position qui est décalée axialement par rapport audit ensemble
de stator (90) pour positionner ledit organe de pompe (16) dans une position rétractée
à l'intérieur de ladite chambre à fluide hydraulique pour assurer une caractéristique
de faible débit entre ladite entrée de fluide (66) et ladite sortie de décharge (70)
quand ledit organe de pompe (16) est entraîné en rotation par ledit arbre de rotor
(114) à faible vitesse du rotor ;
dans laquelle la rotation dudit organe de pompe (16) à une vitesse élevée de la turbine
provoque le déplacement de ladite unité de rotor (92) dans une seconde position alignée
axialement avec ledit ensemble de stator (90) et entraîne le déplacement dudit organe
de pompe (16) dans une position étendue dans ladite chambre de fluide pour assurer
une caractéristique de débit élevé entre ladite entrée de fluide (66) et ladite sortie
de décharge (70),
dans laquelle ledit dispositif de polarisation (152) est un dispositif de polarisation
mécanique incluant un élément de polarisation (156) configuré de manière à exercer
une précharge sur ladite unité de rotor (92) et ledit corps de pompe (12) inclut une
interface entre ladite entrée de fluide (66) et ladite chambre à fluide hydraulique
définissant une première et une seconde surface de bride (78, 80), dans laquelle ladite
turbine (126) a une première et une seconde surface de jante supérieure (136, 138)
alignée avec lesdites première et seconde surfaces de bride (78, 80) dudit corps de
pompe, dans laquelle un grand espace (Y1) est établi entre ladite première surface
de jante supérieure (136) de ladite turbine (126) et ladite première surface de bride
(78) dudit corps de pompe (12) quand ladite turbine (126) se trouve dans sa position
rétractée, et dans laquelle ledit grand espace (Y1) est configuré pour diminuer le
débit de liquide de refroidissement entre ladite entrée de fluide (66) et ladite sortie
de décharge (70).
2. Pompe à eau électrique selon la revendication 1, dans laquelle un petit espace (Y2)
est établi entre ladite première surface de bride (78) dudit corps de pompe (12) et
ladite première surface de jante (136) de ladite turbine (126) quand ladite turbine
(126) se trouve dans sa position étendue, et dans laquelle ledit petit espace (Y2)
est configuré pour augmenter le débit de liquide de refroidissement entre ladite entrée
de fluide et ladite sortie de décharge.
3. Pompe à eau électrique (10) selon la revendication 1, dans laquelle ledit organe de
polarisation (156) est un ressort hélicoïdal placé entre une portion dudit corps de
pompe (12) et de ladite unité de rotor (92).
4. Pompe à eau électrique (10) selon la revendication 1 à 3, dans laquelle le dispositif
de polarisation mécanique (152) agit entre l'unité de rotor (92) et un composant stationnaire
ou une portion du corps de pompe (12).
5. Pompe à eau électrique (10) selon l'une des revendications 1 à 4, dans laquelle une
saillie annulaire (34) s'étend à partir de la section de plaque d'extrémité (26) du
corps de pompe (12) et une rondelle de butée (154) est fixée à la saillie annulaire
(34) et le dispositif de polarisation (156) agit entre la rondelle de butée (154)
et une portion supérieure de l'unité de rotor (92).
6. Pompe à eau électrique (10) selon la revendication 1, dans laquelle ledit arbre de
rotor (114) peut se déplacer axialement par rapport audit corps de pompe (12) et présente
une première extrémité (114A) soutenue, de manière à pouvoir glisser et pivoter, par
une première bague de guidage (122) et une seconde extrémité (114B) soutenue, de manière
à pouvoir glisser et pivoter, par une seconde bague de guidage (124).
7. Pompe à eau électrique (10) selon la revendication 6, dans laquelle une différence
de pression établie sur ladite turbine en réaction à l'augmentation de la vitesse
de la turbine peut fonctionner pour provoquer le déplacement de ladite turbine (126)
de sa position rétractée dans sa position étendue et dans laquelle un tel mouvement
axial de ladite turbine provoque un mouvement axial simultané de ladite unité de rotor
(92) par rapport audit ensemble de stator (90) depuis sa première position dans sa
seconde position.
8. Pompe à eau électrique selon la revendication 1, dans laquelle une différence de pression
établie sur ledit organe de pompe en réaction à l'augmentation de la vitesse de l'unité
de rotor peut fonctionner pour provoquer le déplacement dudit organe de pompe de sa
position rétractée dans sa position étendue, et dans laquelle un tel mouvement axial
dudit organe de pompe provoque un mouvement axial simultané de ladite unité de rotor
par rapport audit ensemble de stator de sa première position dans sa seconde position.